Apparatus for collecting and analyzing human breath

ABSTRACT

The present invention provides methods of collecting and detecting compounds in a human breath sample, comprising: exhaling into a handheld sample collector to absorb at least one breath compound in an exhaled breath collector of said collector; connecting the handheld sample collector to a breath analyzer; transferring the breath compounds from the exhaled breath collector of the sample collector into the breath analyzer; and detecting breath compounds using two or more sensors. The method may be performed to detect breath compounds for determining health or disease diagnosis, or for drug monitoring.

RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119 to U.S.Provisional Patent Application No. 60/352,322, filed Jan. 29, 2002. Theentire content of the aforementioned application is specificallyincorporated herein by reference.

BACK OF THE INVENTION

1. Field of the Invention

The invention relates to methods for collecting and analyzing exhaledbreath samples for trace compounds, and devices, apparatuses, andsystems for performing such methods.

2. Description of Related Art

Exhaled breath of individuals with some diseases contains distinctivegases, or alveolar gradients compared to air, which differs markedlyfrom the exhaled breath of healthy individuals, i.e. acetone in thebreath of individuals with diabetes (Phillips 1992). In addition,because of the high systemic blood flow to the lungs, ingestedsubstances and/or therapeutic drugs are able to partition across theliquid/gas interface and exhaled proportional to systemic levels, i.e.alcohol. Detection of inflammatory markers in the diagnosis of severalpulmonary diseases, such as asthma and chronic obstructive pulmonarydisease (COPD), could substantially improve the understanding of thepathogenesis of these diseases, improve diagnosis, and identify theefficacy of different therapies. Although progress over the last decadehas improved monitoring of forced expiratory volume (FEV) andspirometry, as well as exhaled carbon dioxide and nitric oxide(Montuschi, Kharitonov et al. 2001), these markers tend to vary greatlyfrom patient to patient. Preliminary studies measuring levels ofrecently identified inflammatory markers in the exhaled breath such asethane and 8-isoprostane using gas chromatography/mass spectrometry(GC/MS) has shown higher magnitude differences in exhaled levels of COPDpatients (ethane 2.77+/−0.25 ppb and 8-isoprostane 40+/−3.1 pg/ml inbreath condensate) compared to healthy patients (ethane 0.88+/−0.09 ppband 8-isoprostane 10.8+/−0.8 pg/ml in breath condensate), suggestingexhaled volatile organic compounds (VOCs) may provide improved markersof COPD and other conditions compared to exhaled NO, CO₂, and H₂O₂(Montuschi, Collins et al. 2000; Paredi, Kharitonov et al. 2000).Exhaled VOC profiles have provided a link to other diseases where highlevels of oxidative stress markers are present, including lung cancer,liver disease, inflammatory bowel disease, rheumatoid arthritis, andschizophrenia (Phillips, Erickson et al. 1995; Phillips, Herrera et al.1999; Phillips, Cataneo et al. 2000). Results of several studies havealso shown that Pseudomonas, Klebsiella pneaumoniae, Proteus mirabolis,Staphylococcus aureus, Enterococcus, Clostrdium, and E. coli emitvolatile compounds into the headspace of cultures, also suggesting thatdiagnosis of patients with these diseases could be performed frommonitoring compounds in the breath (Larsson, Mardh et al. 1978; Labows,McGinley et al. 1980; Pons, Rimbault et al. 1985; Zechman, Aldinger etal. Yu, Hamilton-Kemp et al. 2000; Aathithan, Plant et al. 2001).

Unfortunately, progress in breath testing for various diseases and drugmonitoring is hindered by the technical difficulty of detecting very lowconcentrations of exhaled compounds in the breath (nanomolar orpicomolar concentrations). Research has been reported using breathsampling using large heated tubes (Phillips 1995) and cylindrical(Lewis, Severin et al. 2001) containers to collect desired portions ofthe breath for sampling. Unfortunately, these systems require power forpumping and temperature control limiting their widespread use. Detectionof compounds in the collected breath sample has been described using gaschromatography coupled with mass spectrometry (GC/MS), which aresensitive and selective but also bulky and complicated, as well aspolymer-coated resistor arrays, which have low sensitivity and are notselective with complex mixtures such as the breath, have both beendescribed (Phillips 1997; Lewis, Severin et al. 2001). In addition, a GCsystem for detection of volitile compounds in the breath has also beendescribed with improved sensitivity and selectivity that utilizes breathcollection on a absorbent sample tube and a second chromatography columnfor separation of compounds (Satoh, Yanagida et al. 2002).Unfortunately, though, there are no currently available portable vaporor gas sensor systems that can collect and detect mixtures of volatilecompounds at low levels in breath, as well as separate compounds fromthe large exhaled water content. What is desired is an optimized samplecollection system and superior detection capabilities. In addition, itwould be beneficial if sample collection system and the detection systemwere small in size, ideally hand-held or portable, without compromisingsensitivity and selectivity of the compound of interest for detection.

SUMMARY OF THE INVENTION Features and Advantages of the Invention

The present invention overcomes these and other inherent deficiencies inthe prior art by providing novel breath sample collection and detectionmethods for use in health or disease diagnosis, as well as drugmonitoring. In general, the methods disclosed herein provide a means fordetecting and quantifying one or more compounds of interest in theexhaled breath from a collected sample.

The described processes have the advantages of producing reliableresults from the described system while being portable and requiringminimal energy and space. The invention relates to the discovery thatexhalation can be performed directly onto a sorbent phase, without theuse of large collection tubes and heating equipment, and efficientlycapture breath compounds for analysis. In addition, the use of desorbingcaptured breath compounds onto a first sorbent phase into a secondthermal desorption column with detection using small, inexpensive vaporsensors has not previously been described. First, the sample must becollected onto a sorbent trap before analysis to extract compounds ofinterest over several breaths. It is desirable that a sample collector(SC) be portable, preferably a small handheld device similar to anasthma drug inhaler, that may be used to collect breath samples frompatients and then processed on a central detection system. It is alsodesirable that the SC collect several breaths only the alveolar breathfrom the alveoli of the lungs, which contains the volatile compounds ofinterest, which are present in the lung or have diffused from the blood,and not collect the ‘anatomical deadspace’ originating from the pharynx,trachea and bronchial tree where no gaseous interchange occurs. Finally,since the content of the environmental air may contain lowconcentrations of the compounds of interest, it would also be desirableif a sample of the air that is inhaled may be collected onto a sorbenttrap in a similar manner for comparison.

For detection, a portable, robust detection system that extracts a gassample from the concentrated breath and air samples as desired as analternative to conventional GC/MS systems which are complicated andbulky. An ideal alternative would be a handheld chemical sensor, similarto an electronic nose, which are commercially-available for thedetection of chemical spills and volatile organic compounds (VOC's).Unfortunately, these sensor arrays alone may only be used to detect highconcentrations of volatile compounds (milli-molar) with reducedsensitivity under high humidity conditions such as the exhaled breath.An improved sensor system with high sensitivity, coupled with a breathsample collector, which can be used to recognize simple and/or complexgas mixtures for a variety of exhaled compounds would be a great benefitto the medical field.

The process also has several advantages over previously described breathcollection and analysis techniques including:

-   1. Portable: the breath collection apparatus allows for collection    of the breath sample in any environment, i.e., on the battlefield or    in an emergency room.-   2. User-friendly: the breath collection apparatus is easy to operate    and presents no significant resistance to sampling via inhalation    and exhalation. In addition, the detection system processes the    sample and provides the desired response in an easy-to-operate    interface.-   3. Disposible: the breath collection apparatus provides no possible    exposure to cross-contamination or exposure to infectious pathogens    from another patient.-   4. Efficient sampling: The breath collection apparatus can control    the breath sampling by collecting only the alveolar breath    component, not the dead space.-   5. Concentration of sample: The breath collection apparatus may    allow for the alveolar breath to be sampled over multiple breaths,    thus improving the possibility of detecting compounds of interest    that are present at extremely low concentrations in the breath.

SUMMARY OF THE INVENTION

The present invention provides methods of collecting and detectingcompounds in a human breath sample, comprising: exhaling into a handheldsample collector to absorb at least one breath compound in an exhaledbreath collector of said handheld sample collector; connecting thehandheld sample collector to a breath analyzer; transferring the breathcompounds from the exhaled breath collector of the sample collector intothe breath analyzer; and detecting breath compounds using two or moresensors. The method may be performed to detect breath compounds fordetermining health or disease diagnosis, or for drug monitoring.

The exhaling may comprise multiple exhaled breaths into the exhaledbreath collector of the sample collector, and may contain at least onesorbent phase to absorb breath compounds. The sorbent phase is selectedfrom, but not limited to, activated carbon, silica gel, activatedalumina, molecular sieve carbon, molecular sieve zeolites, silicalite,AlPO₄, alumina, polystyrene, and combinations thereof. The handheldsample collector may further comprise inhaling through an outside, orenvironmental, air collector, which may precede exhaling into theexhaled breath collector. The first portion of the exhaled breath maybypass the exhaled breath collector.

The sample collector may be placed in fluid communication with a breathanalyzer system, and the breath analyzer may separate the breathcompounds using a thermal desorption column.

Detection may be performed using mass spectroscopy, or electronic,optical, or acoustic vapor sensors. Sensors may include at least onesensor selected from the group consisting of surface acoustic wavesensors, shear horizontal wave sensors, flexural plate wave sensors,quartz microbalance sensors, conducting polymer sensors, dye-impregnatedpolymer film on fiber optic detectors, conductive composite sensors,chemiresistors, metal oxide gas sensors, electrochemical gas detectors,chemically sensitive field-effect transistors, and carbon black-polymercomposite devices. The sensors are removable and/or replaceable.

A breath sample may comprise multiple breath compounds, including, butnot limited to, alcohols, ethers, ketones, amines, aldehydes, carbonyls,carbanions, alkanes, alkenes, alkynes, aromatic hydrocarbons,polynuclear aromatics, biomolecules, sugars, isoprenes, isoprenoids,VOCs, VOAs, indoles, pyridines, fatty acids, and off-gases of amicroorganism.

The present invention also provides a profile that may be generated fromthe sensor response, which may be used to prepare a diagnostic profileof a patient. Further, a diagnosis based on the profile may be producedusing the diagnostic method.

In other embodiments, the present invention includes methods ofcollecting and analyzing a human breath sample, comprising: exhalinginto a handheld sample collector; placing the handheld sample collectorin fluid communication with a breath analyzer; transferring compoundsfrom the sample collector into the breath analyzer for separation on athermal desorption column; detecting compounds using two or morepolymer-coated surface acoustic wave sensors; and wherein the handheldsample collector is not in fluid communication with the breath analyzerduring the exhaling.

In other embodiments, the present invention includes an apparatus forcollecting and detecting compounds in a human breath sample comprising:a handheld sample collector; a connector for connecting the handheldsample collector in fluid communication with a breath analyzer; a flowcontroller for transferring the breath compounds from the samplecollector into the breath analyzer; and two or more sensors fordetection of breath compounds.

The apparatus for collecting and detecting compounds in a human breathsample may be used to detect breath compounds for determining health ordisease diagnosis, or for drug monitoring.

The handheld sample collector of the apparatus may collect breathcompounds from multiple breaths. The handheld sample collector maycomprise an exhaled breath collector containing a sorbent phase toabsorb breath compounds from an exhaled breath. The sorbent phase may beselected from activated carbon, silica gel, activated alumina, molecularsieve carbon, molecular sieve zeolites, silicalite, AlPO₄, alumina,polystyrene, and combinations thereof. The handheld sample collector mayfurther comprise an air collector, for compounds in environmental air,for collecting such compounds upon inhaling.

The breath analyzer system of the apparatus may comprise a thermaldesorption column. In addition, the breath analyzer system of theapparatus may contain a mass spectroscopy, or electronic, optical, oracoustic vapor sensors. Electronic, optical, or acoustic vapor sensorsmay include at least one sensor selected from the group consisting ofsurface acoustic wave sensors, shear horizontal wave sensors, flexuralplate wave sensors, quartz microbalance sensors, conducting polymersensors, dye-impregnated polymer film on fiber optic detectors,conductive composite sensors, chemiresistors, metal oxide gas sensors,electrochemical gas detectors, chemically sensitive field-effecttransistors, and carbon black-polymer composite devices.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings form part of the present specification and are included tofurther demonstrate certain aspects of the present invention. Theinvention may be better understood by reference to one or more of thesedrawings in combination with the detailed description of specificembodiments presented herein.

FIG. 1 shows a top view of the breath sample collector with A) therelated passages open upon inhalation, B) the related passages open uponinitial exhalation, and C) the related passages open upon alveolarexhalation.

FIG. 2 is an anatomical illustration depicting the human respiratorysystem and collection of alveloar breath into the sample collector.

FIG. 3 is a general illustration of the design of the breath analyzersystem.

DETAILED DESCRIPTION OF THE INVENTION

The invention is directed to improved methods for collecting humanbreath samples and analyzing collected exhaled samples for compounds anddevices described herein. The invention is also directed to theapplication of such methods in health or disease diagnosis, as well astherapeutic drug monitoring. The present invention utilizes thediscovery that breath samples may be concentrated efficiently onto astable adsorbent particulate phase with low back-pressure, therebyavoiding discomfort for the patient. In addition, the present inventionutilizes efficient detection of the breath sample using multiple sensorssimultaneously, reducing the run-time and accuracy significantly.

In one embodiment, a handheld two-sided sample collector (SC) isdescribed which may be used to concentrate compounds from the exhaledbreath on one side and from the air on the other side. The SC is thenplaced into a breath analyzer (BAS) system which pumps the concentratedbreath sample through a thermal desorption column for separation.Compounds are desorbed from the column, which provides time resolution,and detected using electronic, optical, or acoustic vapor sensors. Thiscombination of sample collection and analysis using portable,user-friendly devices provides an excellent alternative to conventionaldiagnostic techniques that are costly, time-consuming, and oftenunpredictable.

The invention includes several embodiments by which the SC and the BAScan be suitably modified for different applications or to offersensitivity of each for different applications. The resulting samplecollection and detection system may be used for detection for singlebreath compounds or multiple compounds for an overall diagnostic profileof a patient.

Thus, it is an object of the present invention to provide a method forcollecting breath samples using a handheld sample collector with asorbent phase to concentrate compounds from the exhaled breath.

It is a further object of the present invention to provide a method forcollecting breath samples using a handheld sample collector with twosorbent phase compartments to concentrate compounds from the exhaledbreath on one side and from the air on the other side.

It is a further object of the present invention to provide a method forcollecting breath samples using a handheld sample collector thatselectively samples the exhaled breath specifically from the alveolarspace using flow divertor so that the first portion of the breath fromthe anatomical deadspace bypasses the sample collector.

In addition, it is an object of the present invention to provide such ahandheld sample collector that controls sampling of the inhaled andexhaled breath when placed in contact with the mouth, thereby maximizingcollection of compounds in the breath and environmental air. The subjectmay be any breathing animal, preferably a human patient, of interest.

It is another object of the present invention to provide such a handheldsample collector which is easy to use and which has either multiplebreath sampling capabilities, or the ability to be convenientlyreloaded.

It is still another object of the present invention to provide such ahandheld sample collector that is mechanically simple, does not requiredepletable power sources, and which is relatively inexpensive.

The above and other objects of the invention are realized in specificillustrated embodiments of a handheld sample collector having a bodywith an inhalation passage and exhalation passages, which bypassessampling the first portion of breath from the anatomical dead-space, andonly collects breath from the alveolar space. The exhalation passage isformed by a first exhalation channel having a proximal end and a distalend, and a restricting flap or vane disposed near the distal end. Therestricting vane is hinged within the primary exhalation passage toselectively inhibit the flow of air through the first exhalationchannel. Thus, as the user exhales, forcing air from the proximal end tothe distal end of the first exhalation channel, the hinged vane movesinto a position to occlude a substantial portion of the channel, therebylimiting flow through the channel and subsequently into the exhaledbreath collector.

It is a further object of the present invention to provide a method ofanalyzing the concentrated breath and air sample from the samplecollector by using a portable breath analyzer system composed whichthermally desorbs compounds from the sample collector using detection byeither gas chromatography/mass spectroscopy, fiber-optic fluorescentsensors, or surface acoustic wave sensors.

In a variation of the above embodiment, the housing of the portablebreath analyzer system includes a receptacle for the handheld samplecollector, and the sensor module is removably mounted in the receptacleof the housing. In this embodiment, the sensor module can include one ormore sensors.

Another specific embodiment of the invention provides a sensor moduleconfigured for use with a sensing apparatus. The sensor module isdisposed within a housing that defines a receptacle. The sensor moduleincludes a casing, an inlet and outlet connection for the handheldsample collector, a thermal desorption column, at least two sensors, andan electrical connector. The outlet port receives a test sample from thehandheld sample collector and directs the test sample to the samplechamber. The sensors are located within or adjacent to the samplechamber and are configured to provide a distinct response when exposedto one or more analytes located within the handheld sample collector.

Methods for Collecting And Analyzing Human Breath

The method of the present invention generally involves collecting andanalyzing human breath. Techniques for collecting and analyzing gassamples are well-known in the art, and include such methods asenvironmental gas sampling on sorbent tubes, as well as headspace andtrap and purge sampling for gas chromatography and GC/MS analysis.General air sampling systems include smoke detectors, volatile chemicaldetectors, and infrared gas sensors specific to a particular compound(such as C0 ₂). In addition, detection of exhaled gases, such as oxygen,carbon dioxide, and nitric oxide, are typically used in hospitals andemergency rooms to report important patient conditions, as well asbreath alcohol detectors in law enforcement. Specifically, though,detection of specific compounds in a breath sample requires reliablecollection, processing, separation, and data interpretation to produce areliable response.

Several vapor sensing technologies, including conducting polymers,electrochemical cells, gas chromatography/mass spectroscopy, infraredspectroscopy, ion mobility spectrometry, metal oxide semiconductor,photo-ionized detectors and surface acoustic wave sensors, have beenevaluated for detection of compounds in the breath. Sensor sensitivity,selectivity, operating life, shelf-life, drift, linearity, initial cost,recurring costs, warm-up time, analysis time, power consumption,portability and calibration needs were evaluated. Although there is alarge market opportunity to be able to diagnose medical conditionsnon-invasively by monitoring breath, one challenge is identifying thebreath compounds, or analytes, that are present for each medicalcondition and determining if their concentrations are detectable. Inaddition, each person will have different concentrations andcompositions of analytes (inter-patient variability), making analysis ofdiverse populations difficult. Typically, there will also existchemically similar analytes that interfere with the analysis makingselectivity of trace concentrations another important factor. Thus, asensitive and specific sensor platform is needed that is portable andcost effective. The relevant gas sensor technologies are reviewed below(Table 1) comparing the selectivity, sensitivity to humidity, overallsensitivity, drift, size/portability, reproducibility on large scale,energy consumption, and initial and annual costs. The sensor systemsreviewed include: gas chromatography (GC), mass spectroscopy (MS),Fourier-transform infrared spectroscopy (FTIR), metal-oxide sensor(MOS), photo-ionization detection (PID), conductingpolymers/electrochemical (CP/EC), fiber-optic fluorescent sensor (FOFI),surface acoustic wave (SAW), and pre-concentrator/thermal-desorptionsurface acoustic wave (PC/TD SAW). In particular, the FOFI and PC/TD SAWsensors are discussed as particularly strong platforms, compared toGC/MS, for a sensitive commercial product. TABLE 1 Comparison ofdifferent sensor platforms and requirements for a diagnostic system. PC/GC/ CP/ TD MS FTIR MOS PID EC FOFI SAW SAW Compound ++ + − −− − + − ++Selectivity Interferants/ ++ + − − −− + −− ++ Humidity Sens. Sensitivity++ − ++ + + + + ++ Drift − − − − + − + Size/Portable −− −− + + + ++ ++++ Re- − + − ++ + ++ producibility/ Mass Manufact. Power/Energy −− −−− + + ++ ++ ++ Consumption Initial Cost −− −− ++ + + ++ ++ ++ (<$1,000)Annual Cost −− −− ++ − − ++ ++ ++

Gas Chromatograph/Mass Spectroscopy (GC/MS)

Gas chromatography/mass spectroscopy (GC/MS) is actually a combinationof two technologies. One technology separates the chemical components(GC) while the other one detects them (MS). Technically, GC is thephysical separation of two or more compounds based on their differentialdistribution between two phases, the mobile phase and stationary phase.The mobile phase is a carrier gas that moves a vaporized sample througha column coated with a stationary phase where separation takes place.When a separated sample component elutes from the column, a detector,such as a Flame Ionization Detector (FID) or an Electrochemical Detector(ECD), converts the column eluent to an electrical signal that ismeasured and recorded. The signal is recorded as a peak in thechromatogram plot. Chromatograph peaks can be identified from theircorresponding retention times. The retention time is measured from thetime of sample injection to the time of the peak maximum, and isunaffected by the presence of other sample components. Retention timescan range from seconds to hours, depending on the column selected thecomponent, and the temperature gradient. The height of the peak relatesto the concentration of a component in the sample mixture.

Mass spectroscopy is a detection method, which can be coupled with GC orsample directly from the headspace of a sample, which ionizes,fragments, and rearranges a molecule under a given set of conditions andmakes identification of the molecular weight/charge (m/z) of moleculespossible. A mass spectrum is a plot showing the mass/charge ratio versusabundance data for ions from the sample molecule and its fragments. Thedisadvantage of using MS independently from GC is that complex mixtures,such as breath, would provide an assembly of mass peaks that would benearly impossible to interpret.

GC, and the combination of GC/MS, are the most accurate, selective, andsensitive sensor technologies. They are also the most complex systems touse, the most expensive ($50,000 for a base instrument), the leastportable with the slowest analysis time (minutes to hours). Even withsignificant development efforts, the GC/MS system is not a feasiblecommercial breath detection system, although components of GC can beminiaturized with improved detector technologies.

Fiber-Optic Fluorescent Sensors (FOFI)

In a photoluminescent, or fluorescent, type optical sensor, afluorescence molecule is immobilized in a polymer or sol-gel matrix, oronto a microsphere bead, and coated onto the end of optical fiber. Thefluorescent compound, such as ruthenium (McEvoy, McDonagh et al. 1997),or dye, such as Nile Red (Albert, Walt et al. 2001), undergoes anintensity or wavelength shift upon changes in the microenvironment dueto interactions with a volatile compound. The sensor response isprovided by producing an excitation light pulse through an optic fiberand measuring the emission spectra the returns using a spectrometer.Some of the advantages of optical sensor over electrodes includereproducibility, small and light weight, large dynamic range, ease ofmultiplexing, ease of calibration, and low power (LED light source)requirement.

Surface Acoustic Wave (SAW) Sensors

Surface Acoustic Wave (SAW) sensors are constructed with interdigitalmetal electrodes fabricated on piezoelectric substrates both to generateand to detect surface acoustic waves. Surface acoustic waves are wavesthat have their maximum amplitude at the surface and whose energy isnearly all contained within 15 to 20 wavelengths of the surface. Becausethe amplitude is a maximum at the surface such devices are very surfacesensitive. Because of the popularity of cell phones, SAW devices, whichact as electronic bandpass filters in hermetically sealed enclosures,have the highest sensor-to-sensor signal reproducibility of any of thesystems described. In addition, they are small, require low-power, andare low-cost.

SAW chemical sensors take advantage of this surface sensitivity tofunction as sensors. If a SAW device is coated with a thin polymer filmit will affect the frequency and insertion loss of the device. If thedevice, with the chemo-selective polymer coating, is then subjected tochemical vapors that absorb onto the surface, then the frequency andinsertion loss of the device will further change. It is this finalchange from baseline that allows the device to function as a chemicalsensor.

If several SAW devices are each coated with a different polymer materialthrough spray-coat or spin-coat techniques, the response to a givenchemical vapor will vary substantially from device to device based onthe thickness and morphology of the final film, but alternativetechniques of producing reproducible coatings are also available. Thepolymer is normally chosen so that each will have a different chemicalaffinity for a variety of organic chemical classes, i.e., hydrocarbon,alcohol, ketone, oxygenated, chlorinated, and nitrogenated. If thepolymer films are properly chosen, each chemical vapor of interest willhave a unique overall effect on the set of devices. SAW chemical sensorsare useful in the range of organic compounds from hexane on the light,volatile extreme to semi-volatile compounds on the heavy, low volatilityextreme.

Breath Sample Collector (SC)

In general, the breath sample must be concentrated onto a sorbent trapover several breaths to extract low concentration compounds-of-interest.It is desirable that a sample collector (SC) be portable, preferably asmall handheld device similar to an asthma drug inhaler, that may beused to collect breath samples from patients and then processed on acentral detection system that is also portable and user-friendly. It isalso desirable that the SC collect several breaths from the alveoli ofthe lungs, which contain the volatile compounds of interest present inthe lung or have diffused from the blood. Air from the ‘anatomicaldeadspace’ originating from the pharynx, trachea, and bronchial treewhere no gaseous interchange occurs should not be sampled. Finally,since the content of the environmental air may contain lowconcentrations of the compounds of interest, it would also be desirablethat a sample of the air that is inhaled be collected onto a sorbenttrap in a similar manner for comparison.

A SC with a sorbent tube which a patient exhales directly through hasbeen shown to produce excellent absorption and desorption propertiesusing common sorbent phase used in GC. The sorbent tube, typicallyapproximately ¼ inch in diameter and 4 to 10 inches in length, produceslow back-pressure from coarse particulates with minimal moistureabsorption and high collection efficiency. The SC may also use anexhalation cavity, which is designed with one-way flaps to only capturecertain portions of the exhaled breath, to obtain optimum sampling overmultiple breaths. The SC is ideally fashioned with two sorbent tubes forcollection of air upon inhalation and breath compounds upon inhalation,and can be used to flow the inhaled and exhaled gases simultaneously orin two separate sampling phases. The SC can be made of plastic, lowweight and low cost, and may be used in a remote location and attachedto the breath analyzer later for processing.

Breath Analyzer System (BAs)

The gas sample that is introduced into the sensor system, using aheadspace analyzer or a sorbent column, needs to be delivered withoutloss of signal by absorption to tubing and connections. The flow rate ofthe gas sample is regulated to control sampling variability, similar toGC, using a regulated gas supply. Interaction between the captured gassample and gas flow system components, such as valves, pumps, and tubes,are minimized in the system design, i.e. non-adsorbing tubing, valves,etc. We recently observed in an animal study significant losses of anexhaled medication were detected from adsorption to certain types ofporous tubing (unpublished results). For a 4-SAW BAS system, a mini-GCcolumn is used to capture and separate compounds at 100-400 ml/min tooptimize absorption onto the thermal desorption column. Furthermore, thetemperature gradient is ramped from 60° C. to 240° C. over 40-80 secondsto desorb compounds for detection on, for example, a 4-SAW array.Optimization of these conditions for each sample is performed using amathematical model to systematically investigate the effects of columnpacking, column temperature gradient, and gas flow to produce optimizedsampling and analysis systems for a variety of diagnostic profiles.

A miniature gas chromatography (GC) column, or thermal desorption (TD)column, is used to capture vapors of interest from the SC and obtaintime resolution detection. Molecules are absorbed onto the packed TDcolumn as the gas sample flows through it and desorb in atemperature-dependant manner proportional to the vapor pressure of ananalyte. Different molecules desorb at different temperatures, similarto GC, so time resolution of different compounds, proportional to thetemperature gradient, is obtained. Time and the increase in columntemperature yields a time resolution between the desorption of differentmolecules, as well as differences in the response of the 4 differentsensors, resulting in a chromatogram for each sensor. The resulting dataoutput is enhanced using the selectivity to the 4 differentpolymer-coated sensors and allows for recognition between multiplecompounds in the breath or the presence of interferants (such as coffeeor tobacco). In general, the packing material in the TD column, samplingtime, temperature range, and entire gas-flow system will be optimizedfor the analytes of interest, as well as for separation frominterferring species.

An example of the BAS is composed of 3 electronic subsystems include thefollowing modules: (1) SAW oscillation circuits, (2) frequency counters,and (3) the controlling unit. The SAW oscillation circuits areresponsible for generating a baseline resonant frequency based on theparticular polymer coating applied to the SAW and a shifted resonantfrequency based on the adsorption of the sample vapor to the individualpolymer coated SAWs within the sensor array. The frequency counterdetermines the resonant frequency of the SAW resonator circuits andconverts it to a voltage for analysis. The control module is responsiblefor sampling and conditioning input signals as well as multiplexing andtiming communication with external devices.

One configuration to measure SAW responses is to measure the frequencyshifts based on a SAW resonator configuration. This delay line resonatorconfiguration not only requires less circuitry but also gives responseswith vastly superior precision than the pure delay line circuit, whichmeasures amplitude variations compared to an external input signal. Theresonator circuit is simply composed of the SAW sensor and a class Afeedback amplifier with a gain greater than the signal attenuation thatoccurs in the SAW delay line, the SAW interdigital transducer electrodes(IDT), and supporting circuitry. The resonant frequency of the circuitis primarily determined by the SAW delay line characteristics such asdelay line length and substrate material and IDT characteristicsincluding finger amount and spacing. Sensitivity has been shown to beproportional to resonant frequency, however noise also increases withfrequency. Previous studies with SAW devices in the hundreds ofmegahertz range have shown sensitivities into the ppb (parts perbillion) range with comparable sensitivities to GC.

The frequency counter outputs an analog voltage of the formv(t)=G(t)f(t) where v(t) is a real time voltage, f(t) is the resonantfrequency, and G(t) is a device dependent function. The frequencycounter is multiplexed between the different sensors based upon theparticular integrated circuit or device that is used. This analog outputis then converted to digital data via an A/D converter normally on mostcommon digital signal processor (DSP) or microcontroller chips. Thecontrolling unit is composed of common DSP and/or microcontrollers,which provide extremely precise timing abilities as well as on-board A/Dconversion mechanisms, standard communication interfaces such as RS-232,and I/O ports for control mechanisms and memory interfacing.

Feature extraction is the task of extracting relevant signal parameters,such as retention time through the thermal desorption column or sensorresponse ratios, from raw sensor signals. Standard measurements are maderelative to a clean reference headspace sample, such as1-bromo-4-fluoro-benzene. A typical measurement consists of exposing thesensor array to a reference, providing a baseline value, and comparingthe reference to sample runs or adding the reference to the sample at aknown concentration, referred to as an internal standard. Similar to aGC sample run, a compound is introduced onto the column and then a valveswitches allowing flow of the carrier gas, in this case air, across thesensors. As the thermal desorption column ramps to higher temperaturesthe various vapors are desorbed and exposed to the sensors for a giventime (based on the association/dissociation of the vapor for the givenpolymer coating), which causes a change in the output/frequency of the 4different sensors. Retention/desorption times and sensor responses maybe referenced according to the internal standard to better test themodel. The sensor response may span several seconds where the vapordesorbs from the column and the sensors have a rise time where the vaporassociates with each sensor to a maximum and a decay time to return tothe baseline value. From the response curve for each sensor features areextracted. The most common parameters extracted are the retention timeof the peak and the individual sensor responses or ratios from abaseline level.

Apparatus for Collecting and Analyzing Human Breath

Reference will now be made to the drawings in which the various elementsof the present invention will be given numeral designations and in whichthe invention will be discussed so as to enable one skilled in the artto make and use the invention. It is to be understood that the followingdescription is only exemplary of the principles of the presentinvention, and should not be viewed as narrowing the pending claims.

The general design of the breath sample collection (SC) device is shownin FIG. 1A to 1C and an anatomical description of a human exhalingthrough the breath sample collector in FIG. 2. The apparatus shown inFIG. 1A to 1C of the main housing 1 of the handheld sample collectorwith outside air collector 3 and a exhaled breath collector 5. The mouthis placed in contact with the mouthpiece tube 11 that is an oriface witha grating that restricts flow to improve sample collection. Inserted onthe mouthpiece an optional disposible cylinder 31 with a filter forreusing the SC without contamination is provided.

FIG. 1A depicts the air-flow through the air collector 3 and collectionof concentrations of environmental volatile compounds 7 upon inhalation.Upon inhalation air is drawn through the mouthpiece orifice 11 whichopens a vane 21 while vane 23 and 25 remain closed. Air is drawn throughthe rear orifice 13 and through air collector opening 15 and through thestationary collector phase. Environmental volatile compounds 7 arecollected onto the stationary collector phase (shown as 4) and air exitsair collector opening 16, through vane 21, and inhaled throughmouthpiece orifice 11.

FIG. 1B depicts the initial air-flow through the bypass exhalationcavity 2 for avoiding collection of dead-space air upon exhalation. Uponthe initial exhalation, breath flows through the mouthpiece orifice 11which closes vane 21 and opens vane 23 and 25. The stationary collectorphase of exhaled breath collector 5 restricts initial flow uponexhalation and the breath passes through the bypass exhalation passage2. Vane 27, which is designed to close at an assigned flow inconjunction with the mouthpiece oriface 11, is initially open allowingthe first portion of the exhaled breath to flow out rear oriface 13.After the initial portion of the exhaled breath bypasses the exhaledbreath collector 5, vane 27 closes and the exhaled breath is divertedthrough vane 25.

FIG. 1C depicts the collection of volatile compounds of interest in theexhaled breath through the exhaled breath collector 5. After vane 27closes, the exhaled breath is diverted through vane 25 and throughexhaled breath collector opening 17 and through the stationary collectorphase of the exhaled breath collector 5. Exhaled volatile compounds 8are collected onto the stationary collector phase (shown as 6) andbreath exits through opening 18 and out rear orifice 13.

Suitable commercially available adsorbent materials for the collectorshave been investigated (Groves, Zellers et al. 1998) and include, butare not limited to, activated carbon, silica gel, activated alumina,molecular sieve carbon, molecular sieve zeolites, silicalite, AlPO₄,alumina, polystyrene, TENAX series, CARBOTRAP series, CARBOPACK series,CARBOXEN series, CARBOSEIVE series, PORAPAK series, SPHEROCARB series,Dow XUS series, and combinations thereof. Preferred low-pressureadsorbent combinations include, but are not limited to, TENAX TA and GR,CARBOTRAP, and Dow XUS565. Those skilled in the art will know of othersuitable absorbent materials.

An anatomical description of a human exhaling through the breath samplecollector is shown in FIG. 2. As shown, the breath sample of interestfor testing from the alveolar space can be separated from the dead-spaceair in the breath, which typically is the first 100-300 ml of theexhaled breath. For collecting the highest concentration of volatilecompounds of interest present in the breath, several collection factorsmust be optimized including the full expiratory volume (FEV) andexpiratory flow (EF) of the patient, the portion of exhaled breathsampled, type and amount of stationary phase, and the number of breathscollected. Through the optimized design of the SC, (A) the fullexpiratory volume (FEV) and the portion of exhaled breath sampled may beoptimized to fit the general population, (B) the expiratory flow may berestricted through mouthpiece orifice and the type and density of thestationary phases, (C) the number of breaths can be controlled byinserting an optional counter that signals the user that the sampling iscomplete or bypasses all further exhaled breaths to flow through thebypass tube 2 shown in FIG. 1. In addition, it may be of interest tosample the air and the exhaled breath in separate breaths throughmodification of the SC so the alveolar gradient of exhaled volatilecompounds is not reduced through collection after passing through theair collector.

The general apparatus shown in FIG. 3 of the breath analyzer system(BAS) 100 may be used to analyze the air and exhaled breath samplescollected with the SA shown FIGS. 1A to 1C. This design, utilizing a (1)method of connecting the SC 105 to transfer volatile compounds to the(2) thermal desorption column 101 for further separation and thendetection in the (3) sensor module 103, offers several advantagesincluding portability, sensitivity, and reproducibility not previouslyinvestigated. While previously described systems utilize less-sensitiveonline breath detection methods (RYBAK, THEKKADATH et al. 1999;Sunshine, Steinthal et al. 2001) and more cumbersome breath samplingtechniques (Phillips 1995; Lewis, Severin et al. 2001) or collectionbags (Kubo, Morisawa et al. 1999), the described technique takesadvantage of highly efficient collection of compounds in the breath anddetection using a highly sensitive portable detection system.

As depicted in FIG. 3, the breath analyzer system (BAS) 100 is generallysimilar to a GC with motors, pumps, and valves required to bring thesample from the SC 105 into the thermal desorption column 101 forseparation and then detection in the sensor module 103. In the sampleLOAD phase, dry-air or an inert gas 111, which is temperature andhumidity controlled, enters the SC 105 through connection 113. Volatilecompounds move out the SC 105 through connection 115 and through valve107 to the thermal desorption column 101. In a preliminary step adry-air purge that bypasses the thermal desorption column 101 may beperformed by opening valve 119. The gas sample enters the thermaldesorption column 101 through connection 121 which then absorbs to thestationary phase in a similar manner to sample collection. Gas flow inthis phase may be directed over the sensor module 103 or bypassedthrough valve 127. The temperature of the thermal desorption column 101,controlled by a series of NiCr windings 123 around the column or othersuitable heating setup, in this phase is generally below 100° C. forcollection of most compounds on the stationary phase.

During the RUN phase, dry-air or an inert gas sample enters valve 117,bypassing the SC 105, and the thermal desorption column 101 is heated torelease the compounds for detection through valve 107, connection 133,and into the sensor module 103 and out passage 137, over a much shortertime span than generally used for GC. The sensors 135 arrayed in aseries of 2 to more than 32 in the sensor module 103, are monitored forelectrical, acoustic, or optical changes relative to time during therun. Since the sensors 135 are designed to have chemoselectivity todifferent classes of compounds, selectivity of compounds may beperformed through time resolution and sensor response. During the PURGEphase, dry air may be used to purge the thermal desorption column 101entering through valve 117 as well as the sensor module 103 enteringthrough valve 131.

Example sensors for detection in the sensor module include, but are notlimited to, polymer-coated SAW sensors and fiber-optic fluorescencesensors. SAW sensors are reasonably priced (less than $200) and havegood sensitivity (tens of ppm) with very good selectivity. They areportable, robust and consume nominal power. They warm up in less thantwo minutes and require less than one minute for most analysis, andrequire no calibration. SAW sensors do not drift over time, have a longoperating life (greater than five years) and have no known shelf lifeissues. They are sensitive to moisture, but this is eliminated with theuse of the dry-air purge and thermal-desorption column. Fiber-opticfluorescent sensors also have similar properties to SAW sensors ingeneral, but also are disposable since only the tip of the probe isreplaced and no electronics like the SAW sensors. On boardmicroprocessor electronics is required to control the sequences of thesystem and provide the computational power to interpret and analyze datafrom the array. An advantage of this technique, though, is that improvedsensitivity through control of analyte desorption and gas flow, as wellas direct comparison and validation using GC, is possible.

Exhaled Markers of Disease and Oxidative Stress

The analysis of exhaled breath provides an excellent means of assessingVOC's present in the body from a variety of conditions. The rapidequilibration between concentrations in the pulmonary blood supply andin alveolar air is known. The diagnostic potential of breath analysishas been recognized for many years, and links have been establishedbetween specific volatile organic vapor metabolites in the breath andseveral medical conditions (Manolis 1983). In 1971, Pauling found thatnormal human breath contained several hundred different VOCs in lowconcentrations (Pauling, Robinson et al. 1971). Since then, more than athousand different VOCs have been observed employing progressively moresophisticated and sensitive assays in low concentrations in normal humanbreath (Phillips 1997).

In general, normal human alveolar breath contains a large number ofvolatile organic compounds in low concentrations (nanomolar orpicomolar) present from local and systemic cellular biologicalprocessing and metabolism. Therefore, the analysis of breath offers anexcellent platform for the monitoring of various biological states.Another application is the evaluation of exposures to industrialsolvents such as benzene, toluene, styrene (Droz and Guillemin 1986).The non-invasive nature of monitoring exposure of these volitilecompounds by sampling the breath makes it potentially more rapid andconvenient than blood or urine analysis. However, high backgroundconcentrations of water vapor and the presence of certain endogenousorganic vapors make the collection of accurate measurements moredifficult using standard techniques (Groves and Zellers 1996).

Volatile organic compounds (VOCs) may be absorbed and/or metabolizedfrom the inspired air (negative gradient) or added to alveolar breath asproducts of metabolism (positive gradient). Some features of thistransformation have been well understood for many years: e.g., acetoneexhaled in diabetic patients (Manolis 1983) and increased carbon dioxideby metabolism of glucose (Phillips 1992). In addition, there is evidencealveolar breath may be used to diagnose several other disordersincluding lung cancer, liver disease, inflammatory bowel disease,rheumatoid arthritis and schizophrenia (Phillips, Erickson et al. 1995;Phillips, Gleeson et al. 1999; Phillips, Cataneo et al. 2000). Thus, thechemical analysis of breath therefore provides a non-invasive diagnostictest for the diagnosis of these and other diseases.

Volatile Compounds from Bacterial Infection

The 13C-urea breath test is a well known accurate, noninvasive diagnosisof active Helicobacter pylori infection and can document post-therapycure (Opekun, Abdalla et al. 2002). Results of several studies haveshown that Pseudomonas, Klebsiella pneaumoniae, Proteus mirabolis,Staphylococcus aureus, Enterococcus, Clostrdium, E. coli, and M.tuberculosis emit volatile compounds into the headspace of cultures(Larsson, Mardh et al. 1978; Labows, McGinley et al. 1980; Pons,Rimbault et al. 1985; Rimbault, Niel et al. 1986; Zechman, Aldinger etal. 1986; Cundy, Willard et al. 1991; Jenkins, Morris et al. 2000; Yu,Hamilton-Kemp et al. 2000; Aathithan, Plant et al. 2001). The volatileprofiles of cultures of several bacterial strains reveal various acids,alcohols, aldehydes, ketones, and amines using gas chromatography (GC).While direct sampling of the bacteria culture media and swab culturesamples from patients mouths provide more direct ways to detect strainand concentration, breath sampling offers many advantages includingspeed and reproducibility.

First, different strains of bacteria, such as E. coli and Clostridium,are so different biochemically that they emit very characteristiccompounds, which provide a fingerprint for each genus and species. UsingGC techniques, chemical groups or specific compounds have beenidentified as typical volatile metabolites for certain bacteria (Labows,McGinley et al. 1980; Cundy, Willard et al. 1991). For example,Pseudomonas aeruginosa produced a characteristic profile of methylketones (excluding 2-tridecanone) and 1-undecene as a major component;however, no indole was found in this organism (Zechman and Labows 1985;Zechman, Aldinger et al. 1986). Recently, as part of the development ofdigital aroma technology, studied headspace compounds from severalbacteria including P. aeruginosa and E. coli, alcohols including ethanolwere identified as the primary products isolated (Arnold and Senter1998). Second, sampling of the breath offers a non-invasive samplingroute for identification of specific compounds for detection of bacteriaand other organisms, especially for infection in the throat and lungs.

A rapid, non-invasive, and easy-to-use diagnostic system for detectionof tuberculosis (TB), for example, using a patient's breath couldsubstantially improve global control strategies. Although progress overthe last decade has improved the speed and quality of TB diagnosticsystems in industrialized countries, a cost effective system for use inthird-world countries where TB is prevalent is still not available. Thecomposition and concentration of volatile compounds emitted fromTB-infected cells in the lung is largely unknown. However, detection oftuberculostearic acid (TSA) in TB cultures and sputum and serum samplesof TB patients using gas chromatography/mass spectrometry (GC/MS)methods suggests the presence of characteristic metabolites that mightbe useful in diagnosing TB. While direct sampling of a large volume ofexhaled breath of infected patients could be sampled using Tedlar bagsand analyzed with methods such as GC/MS, low bacillary load,patient-to-patient variability, as well as intra-day to inter-daysampling, would most likely not lead to a strong signal to identify acharacteristic profile. Unfortunately, similar to the other exhaledcompounds reviewed for detection, there is the concern that dilutionwith dead-space air and that the lung and throat tissue may absorb andmetabolize a fraction of the emitted volatile compounds. Thus, a breathanalysis system with very low limits of detection (LOD) is described tohelp rapidly diagnose patients in the active disease stage, as well astest response to anti-tuberculosis therapies and vaccines pre andpost-exposure.

Drug Monitoring

The degree of effects from an administered drug, as well as the sideeffects, is directly related to absorption, distribution, metabolism,and elimination (ADME) of the drug at the site-of-action. Theconcentration at the site-of-action determines the therapeutic effects,which for most drugs is related to the systemic levels of the drug inthe blood after oral, injected, inhaled, or administered through otherforms of drug delivery. Therefore, the “drug” will be taken to be anychemical agent that is administered to provide therapeutic effects, oralternatively administered as a diagnostic aid.

Although drugs are administered to provide beneficial therapeuticeffect, often drugs can also cause mild to severe side effects, whichare directly related to the concentration of the drug in the body. Theconcentration of the drug in the body, in turn, is regulated both by theamount of drug ingested by the subject over a given time period, or thedosing regimen, and the rate at which the drug is eliminated from thebody. Therapeutic drug monitoring for improving therapies normallyrequires the collection and analysis of a blood sample. Such tests areinvasive, complex, and require extended time for analysis. While mostdrugs are eliminated renally or hepatically, many drugs and metabolitesare also eliminated through the breath by crossing the liquid:gasbarrier in the lung. Although different levels of a drug would bepresent in the exhaled breath depending on partitioning, breath rate,and physical state of the person and lungs, after factoring losses forcollection and detection variations in the detected breath concentrationversus time should be proportional to the systemic concentrations. Thisinvention provides an excellent, non-invasive means of providinginformation on the systemic drug profile for tailoring drug dose ordosing regimens. Examples of “narrow therapeutic window” drugs or drugswith harmful side effects for which therapeutic drug monitoring is usedinclude bupivacaine, coumadin, cyclosporine, insulin, and anestheticagents such as propofol. In addition, exhaled metabolites or markers ofside effects may also be monitored using the described system, as wellas simply detecting the presence of a drug or marker to monitor patientcompliance to drug regimens. The erythromycin and 13C-urea H. pylonbreath tests are such examples where specific metabolic pathways lead toexhaled products which may provide important markers (Lee, Gwee et al.1998; Rivory, Slaviero et al. 2001). Monitoring of drug levels orflavoring agents may also be performed to monitor adherence to drugregimens after dosing to improve patient outcomes.

EXAMPLES

The following examples are included to demonstrate example embodimentsof the invention. It should be appreciated by those of skill in the artthat the techniques disclosed in the examples which follow representtechniques discovered by the inventors to function well in the practiceof the invention, and thus can be considered to constitute relevantexamples for its practice. However, those of skill in the art should, inlight of the present disclosure, appreciate that many changes can bemade in the specific embodiments which are disclosed and still obtain alike or similar result without departing from the spirit and scope ofthe invention.

Example 1

Menthol Detection

Analysis of a gas sample of menthol was produced in accordance with thepresent invention. Menthol is a common agent in chewing gum andcigarettes. A sample of menthol crystals (200 mg, Spectrum Chemical) wasplaced into a 20 ml glass vial placed into a water bath at 37° C.Breathing was simulated using a Pulmosim (Blease) set for 1000 mlbreaths and a one-way valve connected at the output to produce anexhaled breath every 10 seconds. The vial was connected to the bottom ofa ½″ T-connection and allowed flow to travel over the headspace of thementhol, liquid at 37° C. A stopper was fixed to the other side of theT-connector and a 1 liter Tedlar bag (1 breath) and sorbent tubes (12inches long, ¼″ diameter) with 2 g of Tenax GC (20/35, Alltech) andCarbotrap (20/40, Supelco) were connected for sampling.

The detection system currently utilizes a PC/TD 4-SAW setup as shown inFIG. 3. Three of the four SAW sensors were coated with ethyl-cellulose(A), polyisobutylene (B), and polyepichlorohydrin (C) with acceptablethicknesses (10-50 nm) while one remained uncoated as a control (D). TheSAW resonator frequencies were simultaneously monitored after desorptionfrom the thermal desorption column producing 4 individual profiles withtime of menthol. The thermal desorption/pre-concentrator column (1 inchlong, 1/16″ diameter) was packed with Tenax GC packing and a 40 secondflow was used (at 130 ml/min) for the LOAD phase and an 80 second flow(at 400 ml/min) was used for the RUN phase with a thermal ramp of 2°C./second. The sensor response from the Tedlar bag sample showed twopeaks at 15 and 25 seconds with a sensor affinity of D>C>B>A, andsimilar (but lower) sensor responses following desorption from Tenax andCarbotrap after desorption at 70-80° C. In this fashion, breath samplescould be collected following oral dosing of a menthol-containingformulation (i.e., a tablet or inhaler), or other flavoring agents, andcommunicated to a doctor or pharmacist to confirm that a patient isadhering to a drug regimen at home.

Example 2

Pentane Detection

Analysis of a gas sample of pentane was produced similar to Example 1 inaccordance with the present invention. Polyunsaturated fatty acids arefound in the cellular and subcellular membranes and are prone to lipidperoxidation as a result of the extremely weak binding of the hydrogenatoms to the carbon chain. Increased breath alkanes, particularly ethaneand pentane, have demonstrated increased oxidative stress in breastcancer, rheumatoid arthritis, heart transplant rejection, acutemyocardial infarction, schizophrenia, and bronchial asthma (Phillips1992). A sample of n-pentane (1 ml, Fisher, HPLC grade) was similarlyplaced into a 20 ml glass vial placed into a water bath at 37° C.Samples were collected in a Tedlar bag and onto Tenax GC and Carbotrapsorbent tubes and analyzed using the 4-SAW sensor array. The SAWresonator frequencies were simultaneously monitored after desorptionfrom the thermal desorption column again producing 4 individual profileswith time of pentane. The sensor response from the Tedlar bag and thesorbent tubes showed a single peak at 42 seconds with a sensor affinityof A>C>B=D, and similar (but lower) sensor responses followingdesorption from Tenax and Carbotrap after desorption at 70-80° C. Inthis fashion, breath samples may be analyzed for detection/diagnosis ofvarious disease of oxidative stress.

Example 3

Ethanol Detection

Analysis of a gas sample of ethanol production from E. coli culture wasproduced similar to Example 1 in accordance with the present invention.Ethanol has been previously observed in E. coli fermentation, as well asClostridium, using headspace sampling and GC analysis. One millilitersamples of ethanol, 1-isopropanol (internal standard), and acetic acidstandards, as well as E. coli culture, were similarly placed into a 20ml glass vial placed into a water bath at 37° C. Direct headspacesampling, as well as samples collected in a Tedlar bag and onto Tenax GCand Carbotrap sorbent tubes similar to Example 1, were analyzed usingthe 4-SAW sensor array. GC chromatograms with 1-propanol internalstandard were also identified using a Varian 3600 GC with an HP 19395Aof Lowry broth and E. coli showed peaks corresponding to ethanol, whichis produced by E. coli during the fermentation process, 1-propanol, andacetic acid, which is a component of Lowry broth, at 2.3, 2.8, and 6.5minutes, respectively, on a fused silica column with a temperature rampof 20 degrees/minute. The 4-SAW sensor responses and time resolution forethanol, 1-propanol, and acetic acid standards, as well as E. coliculture, showed varying sensor responses to the polymer coated SAWs foreach low molecular weight compound. The compounds were desorbed quicklyinto the sensor array, with resolution times of 8, 20, and 4 seconds forethanol, 1-propanol, and acetic acid, respectively. Using control of thepre-concentrator thermal profile a stable baseline, short retentiontimes, and affinity for water can be controlled. Also, Tenax-GC thermaldesorption column phase is selective for high boiling compounds such asalcohols, phenols, and monoamines, but other packings such as Carbowax,Porapak, and Chromosorb (Alltech) may be used depending on separation ofthe desired compounds. In this fashion, breath samples may be analyzedfor detection/diagnosis of various bacterial infections from emittedgases, or indirectly from emitted gases such as ammonia from metabolismof urease activity of H. pylori after ingestion of urea. In addition,sampling and storage of breath samples onto sorbent tubes for alcohollevel determination by law enforcement may be performed more accuratelythan before using the described invention.

Example 4

Propofol Detection

Analysis of a gas sample of propofol was produced similar to Example 1in accordance with the present invention. Propofol is an anestheticagent that is infused during surgery and subject to highpatient-to-patient variability in distribution and clearance (Favetta,Degoute et al. 2002). Current multi-gas anesthesia monitors (SAM®Monitor, GE Medical Systems), as well as vital sign monitoring, provideless sensitive and incomplete monitoring during surgery and deaths fromover-anesthetizing patients has been reported (Sear and Higham 2002). Asample of propofol (1 ml, Sigma) was similarly placed into a 20 ml glassvial placed into a water bath at 37° C. Samples were collected in aTedlar bag and onto Tenax GC and Carbotrap sorbent tubes and analyzedusing the 4-SAW sensor array. The SAW resonator frequencies weresimultaneously monitored after desorption from the thermal desorptioncolumn again producing 4 individual profiles with time of propofol. Thesensor response from the Tedlar bag was not present, but sensorresponses direct headspace sampling and from the sorbent tubes showedtwo peaks at 15 and 35 seconds with a sensor affinity of D>A>C>B. Inthis fashion, drug levels may be analyzed from sampling a patientsbreath during anesthesia for monitoring. In addition, other drugs may bedetected directly or metabolic products, such as in 14CO₂ witherythromycin, from analysis of the exhaled breath.

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The following literature citations as well as those cited above areincorporated in pertinent part by reference herein for the reasons citedin the above text:

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1-26. (canceled)
 27. An apparatus for collecting and detecting compoundsin a human breath sample comprising: a handheld sample collectorcomprising a sorbent phase; a breath analyzer comprising a thermaldesorption column; two or more sensors for detection of breathcompounds; and a flow controller for controlling the transfer of breathcompounds from the sample collector into the breath analyzer, whereinthe handheld sample collector and breath analyzer are configured forfluid communication with each other so that breath compounds from thesample collector can pass into the breath analyzer for detection. 28.The apparatus of claim 27, wherein the apparatus is configured to detectat least one breath compound chosen from alcohols, ethers, ketones,amines, aldehydes, carbonyls, carbanions, alkanes, alkenes, alkynes,aromatic hydrocarbons, polynuclear aromatics, biomolecules, sugars,isoprenes, isoprenoids, VOCs, VOAs, indoles, pyridines, fatty acids, andoff-gases of a microorganism
 29. The apparatus of claim 27, wherein theapparatus is configured to detect breath compounds for health or diseasediagnosis.
 30. The apparatus of claim 29, wherein the disease is chosenfrom acute myocardial infarction, asthma, bacterial infection, breastcancer, chronic obstructive pulmonary disease, diabetes, hearttransplant rejection, inflammatory bowel disease, liver disease, lungcancer, rheumatoid arthritis, or schizophrenia.
 31. The apparatus ofclaim 30, wherein the bacterial infection is chosen from Helicobacterpylori, Pseudomonas, Klebsiella pneumoniae, Proteus mirabolis,Staphylococcus aureus, Enterococcus, Clostridium, E. col, and M.tuberculosis infections.
 32. The apparatus of claim 27, wherein theapparatus is configured to detect breath compounds for drug monitoring.33. The apparatus of claim 27, wherein the apparatus is configured todetect breath compounds for determination of exposure to industrialsolvents.
 34. The apparatus of claim 27, wherein the apparatus isconfigured such that the handheld sample collector is not in fluidcommunication with the breath analyzer during sample collection.
 35. Theapparatus of claim 27, wherein the handheld sample collector comprisesan inhalation passage and an exhalation passage.
 36. The apparatus ofclaim 27, wherein the handheld sample collector is configured to collectbreath compounds from multiple breaths.
 37. The apparatus of claim 27,wherein the sorbent phase is selected from activated carbon, silica gel,activated alumina, molecular sieve carbon, molecular sieve zeolites,silicalite, AlPO₄, alumina, polystyrene, and combinations thereof. 38.The apparatus of claim 27, wherein the apparatus further comprises anair collector for collecting compounds in environmental air uponinhaling.
 39. The apparatus of claim 38, wherein the air collectorcomprises a sorbent phase.
 40. The apparatus of claim 27, wherein thesensors comprise at least one sensor selected from the group consistingof mass spectrometers, surface acoustic wave sensors, quartzmicrobalance sensors, conducting polymer sensors, dye-impregnatedpolymer film on fiber optic detectors, conductive composite sensors,chemiresistors, metal oxide gas sensors, electrochemical gas detectors,chemically sensitive field-effect transistors, and carbon black-polymercomposite devices.
 41. The apparatus of claim 27, wherein the sensorsare polymer-coated surface acoustic wave sensors.